Nut and screw drive device of the recirculating ball type



Dec. 18, 1962 B. v.DAv1s 3,068,713

NUT AND scREw DRIVE DEVICE oF TEE RECIECULATING BALL TYPE Filed oct. s,1960I 2 sheds-sheet 1 INVENTOR B RNA D VICTOR DAVIS W f f ATTORNEYS Dec-13, 1952 B. v. DAvls 3,068,713

NUT AND SCREW DRIVE DEVICE OF' THE RECIRCULATING BALL TYPE Filed Oct. 3,1960' A 2 Sheets-Sheet 2 INVENTOR BE NA n vlcToR oAvls BY 2 @4MM/V AT'roEvs United States The invention relates to a nut and screw drive deviceof .the recirculating ball type, and has -for its object to provide forcooling the device when for use in conditions in which it wouldotherwise become undesirably overheated.

According to the invention the nut, or the screw is formed with achamber adapted to receive a ilow of a fluid coolant, and the chambercommunicates through at least one duct with the ball-containing zone todeliver the coolant thereto.

Preferably the delivery end of each duct, breaks through a land whichseparates adjacent turns of the ball half track in the element providedwith the chamber.

In the case where it is the nut which is provided with Ithe chamber, thelatter can be in the form of an eccentric longitudinal bore, and eachduct can extend therefrom in the radially-inward direction of the nut.If the nut in such a case is intended to be supported non-rotatively,and for the screw only to be rotated, the nut can be formed with anexternal union for conducting the supply of coolant to the chamber.

In the case where it is the screw which is provided with the chamber,the latter can be provided by an axial bore in the screw, one end of thebore being adapted -to receive the ow of coolant and the other beingsealed, and each duct can be extended from the bore in theradially-outward direction.

The coolant intended to be used for certain applications of the deviceis CO2 in gaseous form, and in such a case'it would be arranged for thegas to be circulated (eg. by a pump) at a sufficient rate for eiectingthe desired degree of cooling.

Two embodiments of theinvention are now described with reference to theaccompanying drawings, in which:

FIGURE 1 is a longitudinal section through a nut and screw drive deviceaccording to my specication Serial No.' 3,354, led January 19, 1960, nowabandoned, adapted for the nut to receive the ilow of coolant, thesection Being er1-the une 1-1 of FIGURE;

FIGURE 2 is yan end elevation looking 'from the righthand side of FIGURE1;

FIGURE 3 is a longitudinal section through a nut and screw deviceaccordingto the specification of my c opending application adapted forthe screw to receive the ow of coolant, the section being on the line3-3 of FIGURE 4; and

IGURE 4 is an end elevation from the left-hand side of FIGURE 3.

Referring to FIGURES 1 and 2, the screw is shown at and the nut is shownformed in four coaxial portions 11, 12, 13 and 14. The part 11 spgotsinto the part 12 rand is held by a circle of screws 15 to part 14, andfor the purposes of the present invention the nut is provided with anextra end plate 16 which is held up to part 13 by a circle of screws 17.These last-mentioned screws also secure part 13 to part 12.

The screw and the inner periphery of part 14 are provided wth coacting,helical half-tracks for the balls 18, and the parts 11 `and 13 areprovided with -the means according to specification Serial No. 3,354,filed January 19, 1960, now abandoned, for circulating the balls througha longitudinal transfer duct 19 in part 14.

ateo() i 3,0%,713 Patented Dec. 18, 1962 "ice,

The end plate I16 is provided with va radially-outwardlyextending vunion20 for connectionto an external source of CO2 gas, and ia bore 21 of theunion communicates with an `annulus 22 which is formed in that end ofthe plate 16 which abuts the part 13. A sealing ring 23 is provided forpreventing radially-outward escape of the gas from this vicinity.

Reference to FIGURE 2 shows that the part 14 is pro. vided withlongitudinally-extending channels 24 in its outer periphery, leavingbetween them lands 25 for centering it in the part 12. It will be seenthat the ball transfer duct 19 is in one of these lands. These channelsare open at one end to the -annulus 22 but have their other ends closedby the pant 11. Seals 26 and 2.7 respec-` tively prevent radial outwardesc-ape of the gas between parts 11 @and 12, yand parts 12 'and 13,

The bottom of each of the channels Z4 .is provided with a row ofradially-inwardly directed ducts 28 which are fed from the channelthrough respectiverestrictors 29 and break through the centre of ahelical land 30 separating the turns of the ball half-track in part 14.The ducts 2S of each channel deliver the coolant gas to the whole lengthof the screw facing them, and as the channels are spacedcircumierentially of thescrew the latter is subjected to the cooling allround its circumference, the cooling gas delivered through the ductsentering the clearance between the screw and par-t 14. After it hasserved ,its purpose the gas can be allowed to leak out of the ends ofthe clearance round the screw.

In FIGURES 3 and 4 the screw 10a has reduceddiameter ends forming -ashaft on which'are arranged parts 32 Iand 33 provided with means,according to the specilication of my co-pending application fortransierring the balls through a longitudinal duct 34 in the screw. Thenut is shown at 35.

For adapting this construction to the present invention the screw isformed with a coaxial bore 36 of which one end is plugged 4at 37 randthe other adapted for connection to a source of CO2 gas. The bore 36 isprovided with `singularly-spaced ser-ies (two only of which are shown)of ducts 38 which deliver the gas to the centre of the flat-topped,helical land 39 which separates the turns of the ball half-track in thescrew. As in the previously described construction the gas cancirculatethroughout the clearance between the nut and screw and is thena1- lowed to escape out of the ends of the nut.

yl. A drive mechanism ofV the recirculating ball 'type comprising a nutmember provided with an internal helical groove, -a screw memberextending through said nut member-with clearance therebetween, saidscrew member including a complementaryl external helical groove which isadapted to co-operate with the helical groove in said nut member to forma helical guideway, portions of said screw member being reduced indiameter so as to form a pair of axially spaced, outwardly facingshoulders on the outer periphery of said screw member, a pair of collarsseated on the reduced portions of said screw member, said collars havingfaces opposite from and abutting said said shoulders, a longitudinallyextending ball return passage in said screw member, laterally extendingchannels formed in the faces of said collars and inthe walls of saidshoulders which co-operate to form laterally extending passageways whichintersect on one end the ends of said ball return passage and on theother end the aforesaid helical guideway, a substantially continuousendless row of balls extending through the return passage, its laterallyextending passageways and round the helical guideway, an axiallyextending bore in saidrscrew member providing `a coolant carryingpassage therein, one end of said bore being opened and the other endclosed, a plurality of radially extending ducts arranged in axiallyspaced bore 'and the clearance vbetween said nut member and screw memberfor delivering the coolant in said bore Vto dcl'e'a'rancfe" Between the:'ends of,V said nut 'member 'W irige'seap'e'ports 'for theic'oolant. Y,A v y dendincl'im'l Awherein'the col arsfalre'fasteredltol s-aid'sc'rewbyT a=plrality of threaded fasteners. l Y N y y r 357A drivernf'eclahismof the-'iecirclatig ballity'pe comprising a'nut. member of substantiallycircular icrosssectiof'n "andfhichlis provided )with an'internal helicalgrovega screw member of 'substantiallyv circular cross- 'ionjextendingythrough said :nutY membervvith clearance hetweemsaidY screwmemb'erinludinga complenientaryxternalhelicallgroovewhichis adapted tocoperat'e'ivvi-th Vthe helical groove in `said 'nut membergto f'oirn la(elical ignid'eway of substantial'lycircular crosssec'tic'n;i portis ofsaid 'screw 'mmber'being reduced in ldiameter to form a-pairofaXi-allyf'spaced, outwardly ienibenapair ofannnlar collars seated onthereduced portionshffsaidscrew member, said collars'having an outside?diameterfsubstanallyjeqal -tothe diameter yof said's'crew'memberintermediate -sid'shoulders, *sai-d vco1- thev aforesaid,clearanceY andthe helical guide-way, y the l 75. A drive mechanism of l e type-fcomprising an outer-sleeve, an innerssleeve'forming anni received insaid outer sleeve and provided with an internal helical groove, saidVinner sleeve beingrin surface-to-s'urface yengagement with the innerperiphery of said outer sleeve,

"a first annular end plate' 'oneonefend of said `sleeves secured tosaid' inner sleeve, a'secodannnlareridplate on fthe other end V`of saidVsleeves secured to"y said outer sleeve, a S'Cw extendingvrthrjfliellSaid nirisleie an@ Plates and provided with clearancetherebetween, Asaid screw including a complementary external helicalgroove which is adapted to cooperate *Withi theh'el-ic'al groove in saidinner'sleevel to'form a helical guide-way, Va series of balls l i Y insaid `gide`way said'balls bengfin'rolling inter-engageof'cirular'crss'sectyion infsaid screw Ymember and having 'ani parallel fo and'spaced radiallyr'from' the' aXis 'of 'Y Y`=saidffscrew`r1`embenlaterally extending'channels formed lin hefacesofrsaidcollars -and'in the Walls of said shouldersvvliich'fco-operate ,toi-formlaterally extending substandally curved:passageways 'of .substah'tiallyr circular 'ger s's's'ectionWhichfgradual-ly and'smoothly intersectV on on end the'enlds" said ballreturn passage and' intersect on tlieother en {theafore'said helicalguideway, al plurali-ty of 'fastenersbemeen'said collars Vand said screwmember for maintaininglthe kfaces o f `said V'collars insurface-'to-surface contact with the shonlders'jon said screw member, aksillastantially continuous endles'srow of balls extending through' thevreturn passage,-V its Ylaterally fex- "tending passageways and Vronnd"thej helicalguideway, an axially extending bore in said screw memberproviding a'jcoiolantfarryng passage therein,` one end 'of said boreradially extending ductsarrn'ged in airliallyspa'cedfserieslin'sa-idiscrew member and extending-'between sd boreyand?thecle'ai'ance' betvveenflsaidfnut member andjscewmemberlforeelivenngme coolant insaid hereto 'the aforesaid clearance'an'dthe"helicalfguidelway, the 'aforesaid clearance lbetween ,the vendsof gsaid nu-temember and bfeakiihrenghthe :lande provided on saidscrew'V between Vment with said -grooves, a l"plurality, ofcir'cni'nferentially arranged, longitudinallyfextendinghbolantfarifyngfchnnels on the outer `periphery Vof said innersleverlsaid channels being separated by longitudinally extendinglndswhich* arein' srfac'etoisurface yen'gagererrtwith theV inner surface ofsaid outer-sleeve, Vthe circ'nm'ferentialivvdthf Vsaid landsbeing"substantiallysniallertlan'the'ircuif a ferentialwidth of E'said"channels, said" channlsbing opened` atone end and closed at theotlienendjaplufality o f radially feX-tending duct-s 'T arang'e'd vinaxially S'I'Jced series in said inner lsleeve"and eXteldig betweenchannels the'cle'arnce betvveensi Sinner sleevefandl scrievvtcrdelivering :the "cfoolantin s'aid clin'nelsto' theVafor'esaiqltclearance'ian'd the helialgnideavay,"the'clearf Y ancebetween the end s of said inner'sleeve'fandsaid" screw inner @nassersaidr piuraiify of f radially* extendiiifgiders breakthrough tlelflandsprovide'dbn saidut vlfi'efv'ven

